/Engine/Source/Runtime/Slate/Public/Widgets/SViewport.h
TOUCH and GESTURES Called when the user performs a gesture on trackpad. This event is bubbled.
Returns whether the event was handled, along with other possible actions
virtual [FReply](API\Runtime\SlateCore\Input\FReply) OnTouchGesture ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & GestureEvent )